1. Field of the Invention
The present invention relates to flame retardant, light stable compositions--particularly fibers and textile structures--and to their preparation.
2. Description of Background and Other Information
Flame retardancy has become a major consideration, with respect to materials having industrial, commercial, and household applications. For example, polyolefins, including polyolefin plastics, can be highly flammable; accordingly, for products prepared from these substances--e.g., fibers and fabrics, used in products such as clothing, upholstery, and carpeting--the significance of flame retardancy is especially evident.
One means for imparting flame retardancy to polyolefins is by the incorporation of flame retardant additives; these are generally halogenated. Among the halogenated substances, found to have utility as flame retardants, are halogenated hydrocarbyl phosphate and phosphonate esters.
Such compounds appropriate for this purpose include those disclosed in Japanese Patent Publication No. 48-4374, published Feb. 7, 1973, in U.S. Pat. No. 4,714,771, and in Chapter 17, "Brominated Phosphate Ester Flame Retardants for Engineering Thermoplastics", Joseph GREEN, Fire and Polymers--Hazards Identification and Prevention, ACS Symposium Series 425, Gordon R. Nelson, Editor, American Chemical Society, Washington, D.C., 1990. Reoflam.RTM. PB-370 and Reoflam.RTM. PB-460, from FMC Corporation, Philadelphia, Pa., are commercially available brominated hydrocarbyl phosphate ester flame retardants.
Resistance to degradation by UV light, or UV light stability, is also a desirable property for polyolefin products--including, as above, those prepared from fibers and fabrics of polyolefins. UV light stabilizers are correspondingly likewise incorporated with the polyolefins, to impart this property; suitable such substances include the hindered amine light stabilizers (known in the art as HALS).
To provide the properties of flame retardancy and light stability simultaneously, flame retardants and hindered amine light stabilizers have been employed together in polyolefin compositions. However, the halogenated flame retardants have been found to interfere with the function of hindered amine light stabilizers.
Where this interference occurs, the flame retardant forms acid bodies which react with the amine from the light stabilizer, destroying its ability to stabilize against UV radiation. Specifically, these acid bodies attack the active sites of the hindered amine, thereby robbing it of its stabilizing function.
Hindered amine light stabilizers which have been found to resist this deleterious interaction are the alkoxyamine functional hindered amine light stabilizers, these being identified as NOR HALS and as alkoxy-blocked HALS, in "A Novel Nonreactive HALS Boosts Polyolefin Stability", Robert GRAY, Plastics Engineering, June, 1991, and "UV Stabilization of Polypropylene Fiber", Robert GRAY, Proceedings of Polypropylene Technology Conference, Clemson University, Sep. 4-5, 1991. These publications disclose combinations of halogenated flame retardants and alkoxyamine functional hindered amine light stabilizers.
However, another disadvantageous phenomenon associated with halogenated flame retardants is their unfavorable effect upon the luster, or shine, of polyolefin products--particularly, fibers and fabrics. Even where halogenated flame retardants and alkoxyamine functional hindered amine light stabilizers, used together, are characterized by significant resistance to the degradation by UV light, delustering can still occur, because of the action of the flame retardant. This delustering prevents effective commercial utilization, because of the need to match fiber and fabric appearance, in color aesthetics.
It has been discovered that where the halogenated hydrocarbyl phosphate and phosphonate ester flame retardants are employed, in combination with a light stabilizer component including alkoxyamine functional hindered amine, not only is the requisite UV light stability achieved, but the delustering resulting from use of other flame retardants does not occur; this desirable combination of properties results, not only where light stabilization is provided by alkoxyamine functional hindered amine alone, but also where such alkoxyamine functional hindered amine is employed in conjunction with other hindered amine light stabilizers. This is of particular benefit, for polyolefin products which have flame retardancy, light stabilization, and color requirements.